PDCP Entity SDU Deletion for 5G Transmission Queue Management
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Solution Overview
Problem
In 5G data transmission, discarding data packets can cause Sequence Number (SN) gaps, leading to disorder or delay in data transmission and reception due to missing SN information, especially when SDUs are not transmitted within a set time to the RLC layer.
Innovation Solution
A method and apparatus that enable the data packet deletion function at the PDCP entity, where configuration information from the base station indicates whether the deletion function is enabled, and if so, records the transmission duration of SDUs; if the duration exceeds a preset limit, the corresponding SDU is deleted to prevent SN gaps and maintain efficient data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data packet deletion function is enabled at PDCP entity to manage transmission queue, then transmission efficiency is improved, but SN gaps occur causing data transmission disorder
Solution Approach 1:
The patent implements Active Queue Management by discarding SDUs that exceed the maximum transmission duration threshold. The PDCP entity monitors the transmission duration of each SDU and deletes those that have not been transmitted to the RLC layer within the configured time limit. This selective discarding prevents buffer overflow and maintains transmission efficiency while the patent acknowledges the resulting SN gaps as an acceptable trade-off for queue management
Solution Approach 2:
The patent introduces a configurable maximum transmission duration parameter (t_Max) that controls the lifetime of SDUs in the PDCP transmission buffer. By adjusting this time parameter, the system can dynamically balance between maintaining SDUs for potential transmission (improving reliability) and removing them to free buffer space (improving productivity). The base station can configure different t_Max values based on network conditions and service requirements
2Reliability
If SDU transmission duration is extended to ensure complete data delivery, then data completeness is improved, but buffer occupancy increases causing transmission delays
Solution Approach 1:
The patent implements a periodic monitoring mechanism where the PDCP entity continuously checks the transmission duration of SDUs against the maximum threshold. This periodic assessment ensures that SDUs are not held indefinitely in the buffer, preventing excessive buffer occupancy and associated delays. The mechanism periodically removes expired SDUs, maintaining a balance between data completeness and transmission timeliness
3Device complexity
If data packet deletion is implemented to control buffer size, then buffer management efficiency is improved, but SN gaps cause receiving sequence determination errors
Solution Approach 1:
The patent implements feedback mechanisms where the PDCP entity monitors transmission status and provides information about deleted SDUs to higher layers. The base station receives feedback about SN gaps and can adjust configuration parameters accordingly. This feedback loop helps manage the complexity of buffer control while providing visibility into sequence number gaps, allowing the system to adapt to transmission conditions
Data Source
AI summary
Provided are a method for data transmission and apparatus. The method includes: receiving configuration information from a base station, the configuration information indicating whether a data packet deletion function is enabled at a PDCP entity corresponding to a preset data bearer. When the data packet deletion function is enabled, a duration for transmission of SDUs is recorded when the SDUs are transmitted from the PDCP entity corresponding to the preset data bearer to a RLC layer. A first SDU that has not yet been transmitted to the RLC layer is determined from the SDUs in a case that the duration for transmission of the SDUs is longer than a preset duration. The first SDU is deleted.